Observations

Description

Valves are widely lanceolate, with acutely rounded apices. The raphe is undulate and complex. The proximal raphe ends are expanded. The axial area is relatively narrow and slightly lanceolate. The central area is a small irregular stauros, delimited by 5-7 unevenly shortened striae on each side. Striae are radiate throughout, becoming most strongly radiate at the apices. Striae are uniseriate in the central region, with nearly square areolae arranged in distinguishable pairs, 22-24 areolae in 10 µm. Striae become biseriate, with more densely spaced areolae, 25-28 areolae in 10 µm, at the valve margin.

Valve lanceolate with slightly attenuate, semi-rostrate, rounded ends. Axial area narrow. Raphe undulate. Central area transverse, irregular in shape. Striae radiate throughout the valve; irregular in length about central area; may be alternately long and short; broken to form irregular longi-tudinal lines. On the margins of the valve, the striae sometimes give the appearance of being composed of two rows of puncta. Striae, 11-12 in 10 μ. Length 44-45 μ (type, 45 μ). Breadth 15-16 μ (type, 15 μ).

This specimen belongs in the same group as N. tuscula. It is similar to N. constantini Skv. in both the structure of the striae and the raphe, which is undulate.

Specimen illustrated.–A-G.C. 44496
Type locality.–South Carolina, Aiken County, Savannah River at Mile 175 from the mouth of the river, October, 1953.
Distribution.–Known only from the type locality.

Original Images

Cite This Page: Tyree, M. (2017). Aneumastus carolinianus. In Diatoms of the United States. Retrieved March 18, 2018, from http://westerndiatoms.colorado.edu/taxa/species/aneumastus_carolinianus

Valves are lanceolate with acutely rounded apices. The central area is transversely expanded, forming an irregular stauros. The raphe is undulate. Striae are radiate throughout, becoming most strongly radiate at the apices. Striae are uniseriate, except at the margins, where they become biseriate.

Compare

Aneumastus carolinianus differs from both A. rostratus and A. tusculus by its acutely rounded, not protracted apices. A. carolinianus is further distinguished from A. rostratus by its paired arrangement of uniseriate areolae at center valve and less punctate areolae overall. A carolinianus can be further distinguished from A. tusculus by its narrower valves and lacking a regular stauroid central area.

Citations

Patrick, R.M. (1959).New species and nomenclatural changes in the genus Navicula (Bacillariophyceae).
Proceedings of the Academy of Natural Sciences of Philadelphia 111 (1959): 91-108 .http://www.jstor.org/stable/4064508

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)

NADED ID:

Autecology Discussion

Aneumastus caroliniana was described from South Carolina, but has been reported from the Great Lakes (Stoermer et al. 1999). Specimens shown here were collected from two reference-quality streams in West Virginia. This species tends to be uncommon and low in abundance.